Substitution groups for customising code lists

[abcoates@londonmarketsystems.com]

Jon asked me to send this to the list. 

 ------- Forwarded message -------
From: abcoates@londonmarketsystems.com
To: jon.bosak@sun.com, Burnsmarty@aol.com
Subject: Re: Tomorrow's discussion of code lists
Date: Wed, 27 Jul 2005 16:02:28 +0100 

Jon, Marty, I'm at the CSW XML Summer School in Oxford, and phone
difficulties mean I won't be able to phone in today.  I'll leave technical
details to Marty, but I had a look over the weekend at the issue of
providing "hooks" for substitution groups for code lists, and I came to the
following conclusion: 

Supporting substitution groups as a mechanism for customising UBL code lists
means that UBL will have to *passively contain* substitution group
definitions, one for each code list.  However, it is important to understand
that the UBL Schemas will not *actively use* substitution groups, that they
will only passively contain them.  What that means is that the UBL Schemas
will contain substitution group definitions in a way which *does not change*
the way documents are validated by the UBL Schemas. 

I believe this is an acceptable compromise.  The one negative aspect to this
is that the UBL Schemas will require XML Schema validators to behave
consistently when faced with this trivial passive usage of substitution
groups.  Although we haven't tested this yet, I believe we will have no
trouble testing this as part of our normal testing, and I think the risks
are minimal.  That said, we need to finalise that actual proposed code list
Schema structure and test it ASAP, to give people confidence. 

Cheers, Tony. 

-- 
Anthony B. Coates
London Market Systems Limited
33 Throgmorton Street, London, EC2N 2BR, UK
http://www.londonmarketsystems.com/
mailto:abcoates@londonmarketsystems.com
Mobile/Cell: +44 (79) 0543 9026
[MDDL Editor (Market Data Definition Language), http://www.mddl.org/]
[FpML Arch WG Member (Financial Products Markup Language), 
http://www.fpml.org/]
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